Question

我一直在使用以下win32控制台代码尝试使用Boost Spirit语法模板解析嵌入在C ++中的B机器语法。我是一个相对较新的Boost用户。代码编译，但是当我运行VC ++ 2008生成的.exe文件时，程序部分解析输入文件。我认为问题在于我的语法定义或附加为语义的函数。

代码如下：

// BIFAnalyser.cpp : Defines the entry point for the console application.
//
//
/*=============================================================================
    Copyright (c) Temitope Jos Onunkun 2010 
    http://www.dcs.kcl.ac.uk/pg/onun/

    Use, modification and distribution is subject to the Boost Software
    License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
    http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
////////////////////////////////////////////////////////////////////////////
//                                                                        //
//  B Machine parser using the Boost "Grammar" and "Semantic Actions".    // 
//                                                                        //
////////////////////////////////////////////////////////////////////////////

#include <boost/spirit/core.hpp>
#include <boost/tokenizer.hpp>
#include <iostream>
#include <string>
#include <fstream>
#include <vector>
#include <utility>

///////////////////////////////////////////////////////////////////////////////////////////
using namespace std;
using namespace boost::spirit;

///////////////////////////////////////////////////////////////////////////////////////////
//
//  Semantic actions
//
////////////////////////////////////////////////////////////////////////////
vector<string> strVect;


namespace 
{
 //semantic action function on individual lexeme
    void    do_noint(char const* str, char const* end)
    {
        string  s(str, end);

  if(atoi(str))
  {
   ;
  }
  else
  {
  strVect.push_back(s);
        cout << "PUSH(" << s << ')' << endl;
  }
    }

 //semantic action function on addition of lexemes
void do_add(char const*, char const*)    
{ 
 cout << "ADD" << endl; 
 for(vector<string>::iterator vi = strVect.begin(); vi < strVect.end(); ++vi)
   cout << *vi << " ";
}

 //semantic action function on subtraction of lexemes
void do_subt(char const*, char const*)   
{ 
 cout << "SUBTRACT" << endl; 
 for(vector<string>::iterator vi = strVect.begin(); vi < strVect.end(); ++vi)
   cout << *vi << " ";
}

 //semantic action function on multiplication of lexemes
void do_mult(char const*, char const*)   
{ 
 cout << "\nMULTIPLY" << endl; 
 for(vector<string>::iterator vi = strVect.begin(); vi < strVect.end(); ++vi)
   cout << *vi << " ";
 cout << "\n";
}

 //semantic action function on division of lexemes
void do_div(char const*, char const*)    
{ 
 cout << "\nDIVIDE" << endl; 
 for(vector<string>::iterator vi = strVect.begin(); vi < strVect.end(); ++vi)
   cout << *vi << " ";
}

 //semantic action function on simple substitution
void do_sSubst(char const* str, char const* end)    
{ 
   string  s(str, end);

  //use boost tokenizer to break down tokens
 typedef boost::tokenizer<boost::char_separator<char> > Tokenizer;
 boost::char_separator<char> sep("-+/*:=()"); // default char separator
      Tokenizer tok(s, sep);
 Tokenizer::iterator tok_iter = tok.begin();

pair<string, string > dependency; //create a pair object for dependencies

  //save first variable token in simple substitution
 dependency.first = *tok.begin();

  //create a vector object to store all tokens 
 vector<string> dx;
    // 
      for( ; tok_iter != tok.end(); ++tok_iter)  //save all tokens in vector
  {
   dx.push_back(*tok_iter );
  }

 vector<string> d_hat; //stores set of dependency pairs

 string dep; //pairs variables as string object



 for(int unsigned i=1; i < dx.size()-1; i++)
 {
        dependency.second = dx.at(i);
     dep = dependency.first + "|->" + dependency.second + " ";
   d_hat.push_back(dep);
 }


 cout << "PUSH(" << s << ')' << endl;

 for(int unsigned i=0; i < d_hat.size(); i++)
    cout <<"\n...\n" << d_hat.at(i) << " ";

 cout << "\nSIMPLE SUBSTITUTION\n";  

}

    //semantic action function on multiple substitution
void do_mSubst(char const* str, char const* end)    
{ 
  string  s(str, end);

  //use boost tokenizer to break down tokens
  typedef boost::tokenizer<boost::char_separator<char> > Tok;
  boost::char_separator<char> sep("-+/*:=()"); // default char separator
  Tok tok(s, sep);
  Tok::iterator tok_iter = tok.begin();

 // string start = *tok.begin();

  vector<string> mx;

  for( ; tok_iter != tok.end(); ++tok_iter)  //save all tokens in vector
  {
 mx.push_back(*tok_iter );
  }

 mx.push_back("END\n");  //add a marker "end" 

 for(unsigned int i=0; i<mx.size(); i++)
 {
  // if(mx.at(i) == "END" || mx.at(i) == "||" )
  //  break;
  // else if( mx.at(i) == "||")
  //   do_sSubst(str, end); 
  // else 
  // {
  //   do_sSubst(str, end); 

  // }

  cout << "\nTokens ... " << mx.at(i) << " ";
 }


  cout << "PUSH(" << s << ')' << endl;
  cout << "MULTIPLE SUBSTITUTION\n";
 } 

} 

////////////////////////////////////////////////////////////////////////////
//
//  Simple Substitution Grammar
//
////////////////////////////////////////////////////////////////////////////

//  Simple substitution grammar parser with integer values removed
struct Substitution : public grammar<Substitution>
{
    template <typename ScannerT>
    struct definition
    {
        definition(Substitution const& )
        {
  multi_subst 
       = (simple_subst [&do_mSubst]
       >> +( str_p("||") >> simple_subst [&do_mSubst])  
       )
       ;

  simple_subst 
    =  (Identifier >> str_p(":=")  
>> expression)[&do_sSubst]
         ;

  Identifier
    = alpha_p >> +alnum_p//[do_noint]
    ;

            expression
                  =   term
                     >> *(   ('+' >> term)[&do_add]
                        |   ('-' >> term)[&do_subt]
                        )
                  ;

            term
                  =   factor
                     >> *(   ('*' >> factor)[&do_mult]
                        |   ('/' >> factor)[&do_div]
                        )
                  ;

            factor
                =   lexeme_d[( (alpha_p >> +alnum_p) | +digit_p)[&do_noint]]
                |   '(' >> expression >> ')'
                |   ('+' >> factor)
                ;
        }
rule<ScannerT> expression, term, factor, Identifier, simple_subst, 
   multi_subst ;

        rule<ScannerT> const&
        start() const 
  { 
   return multi_subst; 
  }
    };
};

////////////////////////////////////////////////////////////////////////////
//
//  Main program
//
////////////////////////////////////////////////////////////////////////////
int
main()
{
    cout << "************************************************************\n\n";
    cout << "\t\t...Machine Parser...\n\n";
    cout << "************************************************************\n\n";
   // cout << "Type an expression...or [q or Q] to quit\n\n";

//prompt for file name to be input
cout << "Please enter a filename...or [q or Q] to quit:\n\n "; 
char strFilename[256]; //file name store as a string object
cin >> strFilename;

ifstream inFile(strFilename); // opens file object for reading
  //output file for truncated machine (operations only)


Substitution elementary_subst;  //  Simple substitution parser object

string str, next;
// inFile.open(strFilename);
while (inFile >> str)
  {
  getline(cin, next);

  str += next;

        if (str.empty() || str[0] == 'q' || str[0] == 'Q')
            break;

        parse_info<> info = parse(str.c_str(), elementary_subst, space_p);

        if (info.full)
        {
            cout << "\n-------------------------\n";
            cout << "Parsing succeeded\n";
            cout << "\n-------------------------\n";
        }
        else
        {
            cout << "\n-------------------------\n";
            cout << "Parsing failed\n";
            cout << "stopped at: \": " << info.stop << "\"\n";
            cout << "\n-------------------------\n";
        }
    }
    cout << "Please enter a filename...or [q or Q] to quit\n";
    cin >> strFilename;


    return 0;
}

The contents of the file I tried to parse, which I named "mf7.txt" is given below:

debt:=(LoanRequest+outstandingLoan1)*20 || newDebt := loanammount-paidammount


The output when I execute the program is:

************************************************************
                ...Machine Parser...
************************************************************
Please enter a filename...or [q or Q] to quit: 
c:\tplat\mf7.txt
PUSH(LoanRequest)
PUSH(outstandingLoan1)
ADD
LoanRequest outstandingLoan1
MULTIPLY
LoanRequest outstandingLoan1
PUSH(debt:=(LoanRequest+outstandingLoan1)*20)
...
debt|->LoanRequest
...
debt|->outstandingLoan1
SIMPLE SUBSTITUTION
Tokens ... debt
Tokens ... LoanRequest
Tokens ... outstandingLoan1
Tokens ... 20
Tokens ... END 
PUSH(debt:=(LoanRequest+outstandingLoan1)*20)
MULTIPLE SUBSTITUTION
-------------------------
Parsing failedstopped at: ": "
-------------------------

我的意图是只捕获文件中的变量，我设法做到了“||”串。显然，该程序没有解析超出“||”输入文件中的字符串。我将非常感谢帮助修复语法。请SOS。

Answer 1

我相信你的代码一切都很好。在所有输入都已正确匹配后，解析在尾随空格字符处失败。原因是parse()函数不执行跳过后的步骤（即它不会在最后一个匹配的解析器之后调用跳过解析器）。解决此问题的最简单方法是在语法中添加!end_p：

parse_info<> info = parse(str.c_str(), elementary_subst >> !end_p, space_p);

强制所需的跳过并确保您的输入已完全匹配。

Answer 2

我重新设计了如下语法，这似乎解决了这个问题：

SUBST = multi_choice | machine_subst ;

        multi_choice 
                = machine_subst
                >> +( str_p("[]") >> machine_subst )
                ;


        machine_subst
                = (  multi_subst 
                | simple_subst
                | if_select_pre_subst
                | unbounded_choice )[&do_machSubst]
                ;

... ...

multi_subst =（simple_subst

+（str_p（“||”）＆gt;＆gt; simple_subst）                           ）[＆amp; do_mSubst]                         ;

        simple_subst
                = (identifier
                >> str_p(":=") >> arith_expr) [&do_sSubst]
                ;

        expression
                = predicate
                | logic_expr
                | arith_expr
                ;

        predicate
                = ( logic_expr 
                >> +( ( str_p("&") >> logic_expr )
                |     ( str_p("OR") >> logic_expr ) ) )[&do_predicate]
                ;

        logic_expr 
                = ( identifier
                >> ( (str_p("<") >> arith_expr)
                | (str_p(">")  >> arith_expr)
                | (str_p("/:")  >> arith_expr)
                | (str_p("<:")  >> arith_expr)
                | (str_p("/<:")  >> arith_expr)
                | (str_p("<<:")  >> arith_expr)
                | (str_p("/<<:")  >> arith_expr)
                | (str_p("<=")  >> arith_expr)
                | (str_p("=")  >> arith_expr)
                | (str_p(">=")  >> arith_expr)
                | (str_p("=>")  >> arith_expr) )
                )  [&do_logicExpr]
                ;

... ... 我现在对文件f1.txt和f2.txt使用启动规则“subst”，对f3.txt和f4.txt使用“expression”。

start（）const { 返回; // return machine_subst; //返回表达式; //返回if_select_pre_subst; //返回multi_choice; //返回unbounded_choice; }

我仍在构建语法，所以如果我有任何进一步的问题，我会发布它。

Answer 3

帮助提升语法

3 个答案: